SANAA, Yemen — A month after killing Yemen's former president, the Shiite rebels in charge of much of northern Yemen are consolidating their grip, targeting anyone they suspect of opposing their rule.

The rebels, known as Houthis and widely believed to be aligned with Iran, have multiplied their checkpoints around the capital, residents say. Fighters are searching people's cellphones for images of former leader Ali Abdullah Saleh and for any social-media or chat-group posts that either commemorate Saleh or are critical of the Houthis.

Hundreds of people have been arrested, including journalists deemed sympathetic to Saleh and officials in his political party, the General People's Congress, according to party leaders and political analysts. Some loyalists have been executed or assassinated. Houthi militias are continuing to raid the houses of Saleh's relatives and other supporters.

"Prisons now are filled with the leaders of the GPC," said Adel al-Shujaa, a top party official. "There are arrests and extrajudicial killings being done in secret."

Shujaa fled Yemen and arrived recently in the Egyptian capital, Cairo, after the Houthis sentenced him to death, he said. His relatives are in hiding.

"My family is still in Yemen and in danger," he said. He added, "The Houthis went to my house looking for them. But they did not find them."

A senior Houthi official insisted that the GPC was not being targeted and that the rebel group and Saleh's party remain partners. "The GPC is not Saleh," said Dhaifallah al-Shami, a member of the Houthi's political bureau. "All members of the GPC are carrying out their work normally."

The crackdown has had a chilling effect on Yemeni society and driven up prices of food, fuel and other staple goods amid a widening humanitarian crisis in the Middle East's poorest country. The Houthis' deepening hold may also be making it more difficult to broker a deal to end the country's nearly three-year-long civil war.

"The political scene in Yemen has become more complicated after the killing of Saleh," said Wadah Almuwadda, a political analyst and lawyer. "The chances of peace have minimized now that there is only one player controlling the inside, which is also not recognized internationally."

Yemen's civil conflict began in March 2015, after the Houthis drove President Abed Rabbo Mansour Hadi from the capital and into exile. After his ouster, Saudi Arabia, wary of the Houthis' ties to Iran, led a coalition of regional countries aiming to restore Hadi to power.

Yemen’s former president Ali Abdullah Saleh acknowledges supporters at a rally marking the 35th anniversary of the establishment of his General People’s Congress party, in Sanaa on Aug. 24, 2017. (Khaled Abdullah/Reuters)

Hadi took office when a populist revolt in 2011 — part of the Arab Spring uprisings — ended Saleh's rule after 33 years. Saleh, however, had remained in the country. He had forged an alliance of convenience with the Houthis — he had previously waged six civil wars against them — and returned himself and his party to political prominence.

The conflict has taken an immense human toll. At least 10,000 civilians have been killed, mostly in airstrikes by the Saudi-led coalition, according to the United Nations. Millions of Yemenis are at risk of starving or are in the clutches of a cholera epidemic.

The crisis worsened in November when Saudi Arabia intercepted a Houthi missile targeting the Saudi capital, Riyadh. In retaliation, Saudi Arabia broadened a land, air and sea blockade, preventing even humanitarian supplies from entering Yemen.

The blockade was lifted late last month after widespread international condemnation, including a rare public criticism of the Saudis by President Trump.

Rifts between the Houthis and Saleh's loyalists emerged as early as 2016. In early December, after Saleh publicly turned against his allies, Houthi fighters killed him and distributed a video showing his body. Many analysts predicted more chaos in the aftermath.

For now, it appears that the Houthis' regional enemies, led by Saudi Arabia and the United Arab Emirates, have not capitalized on Saleh's death.

As the Houthis have become more isolated, their control has grown. They have seized several key ministries once headed by GPC officials, including security portfolios. Meanwhile, the GPC itself has fragmented. While Shujaa and other top officials have fled the country, fearing arrest or death, others have stayed and decided to work with the Houthis.

Hisham Sharaf, the minister of foreign affairs and a GPC official, said that "neither myself nor any of the top GPC officials are under house arrest" by the Houthis and that he was free to work. "We are still brothers, and we together are able to manage the situation," said Sharaf, referring to the Houthis.

But Shujaa and other GPC officials said "a very small number" of their members have joined the Houthis. The vast majority of those who have remained in Sanaa consider the bonds between the two groups as irreparably broken, they said.

"We fear to speak freely now," said a GPC member who spoke on the condition of anonymity because of concerns for his security. "These militias feed on killing and spreading fear and chaos. They have no political agenda. If you are not one of them, then you are their enemy. How can they be trusted? They do not believe in partnership."

The fear is also being felt on the streets of Sanaa. Residents said in interviews that they had deleted any compromising photos and messages from their cellphones for fear of being stopped and searched at Houthi checkpoints. Images of Saleh, which used to be ubiquitous in shops, and on walls and cars, have vanished.

Houthi supporters walk past al-Saleh Mosque — renamed the People’s Mosque — on Dec. 7, 2017, as they attend the funeral of Houthi fighters said to have been killed during recent clashes in Sanaa. (Arhab/Epa-Efe/Rex/Shutterstock/Arhab/Epa-Efe/Rex/Shutterstock)

Until recently, Yemenis often talked politics boisterously when they gathered in the evenings to chew khat, the leafy narcotic favored by many in the country. But now, some people are afraid to discuss anything controversial, even inside their own homes. The Houthis also occasionally shut down Internet access and have blocked some social-media sites.

Houthi fighters have occupied Saleh's main residence in the capital. The neighborhood, along with adjacent enclaves, has been barricaded with sandbags — an effort apparently to prevent attack by Saleh loyalists.

They Houthis have also changed the name of the gargantuan mosque that rises above the capital — built by Saleh and named after him — to the People's Mosque. After Friday prayers, the Houthis gather to chant slogans.

Residents who can afford it are stockpiling food in case confrontations erupt between Saleh loyalists and the Houthis.

Shujaa is trying to find a way to bring his family out of Yemen. The Houthis, he said, are hunting them.

"They are still monitoring the place where I live in Yemen," he said.

Raghavan reported from Cairo. Heba Farouk Mahfouz in Cairo contributed to this report.